I just got my dizzy back yesterday from the same shop Kenny went to (Thanks again Kenny for bringing mine with you). Ben confirmed what I always knew was true: too much mechanical advance although he reported much more than I thought was happening: 50 degrees! He got it reigned in to 18 degrees all in at 2800 RPM.
I dropped it in as soon as I got home yesterday morning (a process which still gets frustrating), and wow what a difference in throttle response. It had a real smooth slow rise in RPM from 700 to 2500 when I tested it in the driveway. Driving it around was much better as well, no more detonation on hills. The next step is to get the Vacuum advanced tuned in, it is still advancing too much on the ported vacuum but is much better than before.
All of the threads I have read seem consistent with Pat's account of ported vacuum and the purpose of it is only for those times where more advance is needed at lower RPM (Such as climbing a hill).
I can see the pull arm off of the vacuum diaphragm and have confirmed that max ported vacuum seems to be around 1500 RPM for a very short window. The ported timing is correct, but the pull is too much. Pat is also correct on the hex screw adjustment on the diaphragm, however not all of them have it, mine included. I need to decide if my next step is to replace the diaphragm with an adjustable one or try to limit the vacuum line.
Brian
'67 Falcon Bus/240/C4/Offy DP/MSD Duraspark II/Holley 4160
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